Electro luminescence device and electrophotographic printing system using the same

Abstract

An EL device having an electrode arrangement including first electrodes and at least one row of second electrodes intersecting the first electrodes and energized by a combination of the first and second electrodes. The second electrodes are divided into a plurality of sub-electrode portions. The electrode arrangement is such that the first electrodes each comprise a plurality of segments that are commonly-connected and intersect different sub-electrode portions. Another electrode arrangement is such that the first electrodes are arranged in a belt form and intersect different sub-electrodes portions in a meander manner. The EL device can be applied to an electrophotographic printing system as an optical system for forming a latent image. EL elements are repeatedly energized with the same data to give a sufficient intensity of light on a light sensitive medium, and deenergized for a time in which the intensity is decreased to a low level.

We claim: 
     
       1. An electrophotographic printing system comprising: means movable along a predetermined path and coated with a light sensitive medium,   means for precharging said light sensitive medium,   means for forming a latent image on said light sensitive medium,   means for attaching a printing medium at said latent image formed portions on said light sensitive medium,   means for transferring said attached printing medium from said light sensitive medium, and   means for discharging said light sensitive medium,   said latent image forming means comprising an EL device, means for focusing light emitting from said EL device onto said light sensitive medium and means for controlling the energization of said EL device, said EL device comprising:   a light emitting layer;   a plurality of first electrodes, each comprising a plurality of spaced, electrically connected electrode segments;   a plurality of spaced second electrodes, each comprising a plurality of spaced, electrically connected electrode portions,   said first and second electrodes being arranged on respective opposite sides of said light emitting layer, with each first electrode segment disposed in electro luminescing relationship with respect to a corresponding second electrode portion to form an EL element therebetween, and with each first electrode forming such an EL element with each second electrode, said EL elements being disposed in a single line extending transversely of said path,   whereby an AC energizing pulse supplied by said controlling means between a given first electrode and a given second electrode causes the EL element formed therebetween to emit light to said focusing means.   
     
     
       2. An electrophotographic printing system as set forth in claim 1 wherein said control means comprises a plurality of circuit elements driving respective first electrodes and a plurality of circuit elements driving respective second electrodes. 
     
     
       3. An electrophotographic printing system as set forth in claim 2 wherein said control means is operable for repeatedly energizing said EL elements a predetermined number of times with data for forming a latent image in a predetermined period within a predetermined ON time by supplying AC energizing pulses between said first electrodes and said second electrodes through said driving circuit elements, and for deenergizing said EL elements for a predetermined OFF time. 
     
     
       4. An electrophotographic printing system as set forth in claim 3 wherein said predetermined number of times and said predetermined period are designed to cause emission of a predetermined light intensity sufficient to form said latent image, and said OFF time is designed to permit decrease of said emitted light to a level which will not form a latent image. 
     
     
       5. An electrophotographic printing system as set forth in claim 1 wherein the pitch between adjacent electrode portions of each second electrode is defined by the resolution of the latent image formation. 
     
     
       6. An electrophotographic printing system as set forth in claim 1 wherein said first electrodes are arranged in a belt form, said belt-form first electrodes being disposed to intersect said second electrodes in a meander manner. 
     
     
       7. An electrophotographic printing system as set forth in claim 6 wherein said control means comprises a plurality of circuit elements driving respective first electrodes and a plurality of circuit elements driving respective second electrodes. 
     
     
       8. An electrophotographic printing system as set forth in claim 7 wherein said control means comprises means for arranging the order of data to form a latent image defined by the position of said meander form first electrodes intersecting said second electrodes. 
     
     
       9. An electrophotographic printing system as set forth in claim 8 wherein said control means is operable for repeatedly energizing said EL elements a predetermined number of times with data for forming a latent image in a predetermined period within a predetermined ON time by supplying AC energizing pulses between said first electrodes and said second electrodes through said driving circuit elements, and for deenergizing said EL elements for a predetermined OFF time. 
     
     
       10. An electrophotographic printing system as set forth in claim 9 wherein said predetermined number of times and said predetermined period are designed to cause emission of a predetermined light intensity sufficient to form said latent image, and said OFF time is designed to permit decrease of said emitted light to a level which will not form a latent image. 
     
     
       11. An electrophotographic printing system according to claim 10 wherein the pitch between adjacent electrode portions of said second electrode is defined by the resolution of the latent image formation. 
     
     
       12. An electrophotographic printing system as set forth in claim 6 wherein said meander form of said first electrodes is rectangular in shape. 
     
     
       13. An electrophotographic printing system as set forth in claim 6 wherein said meander form of said first electrodes is trapezoidal in shape. 
     
     
       14. An electrophotographic printing system as set forth in claim 6 wherein said meander form of said first electrodes is semi-circular in shape. 
     
     
       15. An electrophotographic printing system as set forth in claim 1 wherein said second electrodes are arranged in two separate groupings with the groupings spaced apart a predetermined distance to present separate arrays of said EL elements. 
     
     
       16. An electrophotographic printing system as set forth in claim 15 wherein said control means comprises two sets of circuit elements for driving respective first electrodes and two sets of circuit elements for driving respective second electrodes. 
     
     
       17. An electrophotographic printing system as set forth in claim 16 wherein said control means comprises means for alternatively providing the same data to the sets of circuit elements in response to the moving speed of said light sensitive medium so that the same positions on the latter may be exposed twice to the same data. 
     
     
       18. An electrophotographic printing system as set forth in claim 17 wherein said control means is operable for repeatedly energizing said EL elements a predetermined number of times with data for forming a latent image in a predetermined period within a predetermined ON time by supplying AC energizing pulses between said first electrodes and said second electrodes through said driving circuit elements, and for deenergizing said EL elements for a predetermined OFF time. 
     
     
       19. An electrophotographic printing system as set forth in claim 18 wherein said predetermined number of times and said predetermined period are designed to cause emission of a predetermined light intensity sufficient to form said latent image, and said OFF time is designed to permit decrease of said emitted light to a level which will not form a latent image. 
     
     
       20. An electrophotographic printing system as set forth in claim 19 wherein the pitch between adjacent electrode portions of the second electrode is defined by the resolution of the latent image formation. 
     
     
       21. An electrophotographic printing system as set forth in claim 15 wherein said first electrodes are arranged in a belt form, said belt-form first electrodes intersecting each of said second electrodes in a meander manner. 
     
     
       22. An electrophotographic printing system as set forth in claim 21 wherein said control means comprises two sets of circuit elements for driving respective first electrodes and two sets of circuit elements for driving respective second electrodes. 
     
     
       23. An electrophotographic printing system according to claim 22 wherein said control means comprises means for alternatively providing the same data to said sets of control elements in response to the moving speed of the light sensitive medium so that the same positions on the latter are exposed twice to the same data and means for arranging the order of data to form a latent image defined by the position of said meander-form first electrodes intersecting the second electrodes. 
     
     
       24. An electrophotographic printing system as set forth in claim 23 wherein said control means is operable for repeatedly energizing said EL elements a predetermined number of times with data for forming a latent image in a predetermined period within a predetermined ON time by supplying AC energizing pulses between said first electrodes and said second electrodes through said driving circuit elements, and for deenergizing said EL elements for a predetermined OFF time. 
     
     
       25. An electrophotographic printing system as set forth in claim 24 wherein said predetermined number of times and said predetermined period are designed to cause emission of a predetermined light intensity sufficient to form said latent image, and said OFF time is designed to permit decrease of said emitted light to a level which will not form a latent image. 
     
     
       26. An electrophotographic printing system as set forth in claim 25 wherein the pitch between adjacent electrode portions on said second electrode is defined by the resolution of the latent image formation. 
     
     
       27. An electrophotographic printing system as set forth in claim 21 wherein said meander form of said first electrodes is rectangular in shape. 
     
     
       28. An electrophotographic printing system as set forth in claim 21 wherein said meander form of said first electrodes is trapezoidal in shape. 
     
     
       29. An electrophotographic printing system as set forth in claim 21 wherein said meander form of said first electrodes is semi-circular in shape. 
     
     
       30. An elongated plane-illumination type electro luminescence device comprising: a transparent substrate:   first transparent electrode means formed on said substrate;   a light emitting layer embedded in an insulating layer on said first electrode means;   second electrode means formed on said insulating layer on the opposite side of the light emitting layer from said first electrode means,   said first transparent electrode means comprising a plurality of first electrode groups, each including a plurality of spaced, electrically connected electrode segments,   said second electrode means comprising a plurality of spaced second electrode groups, each including a plurality of spaced, electrically connected electrode portions,   said first and second electrode groups being arranged with each first electrode segment disposed in electro luminescing relationship with respect to a corresponding second electrode portion to form an EL element therebetween and with each first electrode group forming such an EL element with each second electrode group, said EL elements being disposed in a single line extending longitudinally of the device; and   control means for supplying an AC energizing pulse between a given first electrode group and a given second electrode group to thereby cause the corresponding EL element formed therebetween to emit light.   
     
     
       31. An electro luminescence device as set forth in claim 30 wherein said first electrode means is arranged in a belt form and disposed to intersect said second electrode means in a meander manner. 
     
     
       32. An electro luminescence device as set forth in claim 31 wherein said meander form of said first electrode groups is rectangular in shape. 
     
     
       33. An electro luminescence device as set forth in claim 31 wherein said meander form of said first electrode means is trapezoidal in shape. 
     
     
       34. An electro luminescence device as set forth in claim 31 wherein said meander form of said first electrode means is semi-circular in shape. 
     
     
       35. An electro luminescence device as set forth in claim 30 wherein said second electrode groups are arranged in two separate groupings with the groupings spaced apart a predetermined distance to present separate arrays of said EL elements. 
     
     
       36. An electro luminescence device as set forth in claim 35 wherein said first electrode means is arranged in a belt form and disposed to intersect each of said second electrode groupings in a meander manner. 
     
     
       37. An electro luminescence device as set forth in claim 36 wherein said meander form of said first electrode means is rectangular in shape. 
     
     
       38. An electro luminescence device as set forth in claim 36 wherein said meander form of said first electrode means is trapezoidal in shape. 
     
     
       39. An electro luminescence device as set forth in claim 36 wherein said meander form of said first electrode means is semi-circular in shape.